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pngunknown fix for multiple IDAT chunks

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Fixes the case where IDAT is treated as unknown and saved; the first IDAT chunk
ends up 'before' IDAT, the rest 'after', pngunknown has to take this into
account since it checks before and after.
This commit is contained in:
John Bowler 2015-11-28 08:42:54 -08:00
parent b3a18efebf
commit 6bbc74d880
1 changed files with 14 additions and 0 deletions
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14
contrib/libtests/pngunknown.c
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@ -1001,6 +1001,20 @@ perform_one_test(FILE *fp, int argc, const char **argv,
def = check(fp, argc, argv, flags[1], d, set_callback); def = check(fp, argc, argv, flags[1], d, set_callback);
/* If IDAT is being handled as unknown the image read is skipped and all the
* IDATs after the first end up in the end info struct, so in this case add
* IDAT to the list of unknowns. (Do this after 'check' above sets the
* chunk_info 'keep' fields.)
*
* Note that the flag setting has to be in the 'known' field to avoid
* triggeriing the consistency check below and the flag must only be set if
* there are multiple IDATs, so if the check above did find an unknown IDAT
* after IDAT.
*/
if (chunk_info[0/*IDAT*/].keep != PNG_HANDLE_CHUNK_AS_DEFAULT &&
(flags[1][3] & PNG_INFO_IDAT) != 0)
flags[0][2] |= PNG_INFO_IDAT;
/* Chunks should either be known or unknown, never both and this should apply /* Chunks should either be known or unknown, never both and this should apply
* whether the chunk is before or after the IDAT (actually, the app can * whether the chunk is before or after the IDAT (actually, the app can
* probably change this by swapping the handling after the image, but this * probably change this by swapping the handling after the image, but this